1. Field of the Invention
The present invention relates to an image capture device and defective pixel detection device adapted to detect, from a plurality of pixels making up the pixels of an image captured by an image capture device, defective pixels that may result for example from improper operation of an image capture element provided to the imaging device; and to a marking device for an image capture device.
2. Description of the Related Art
Image capture devices such as digital still cameras and digital video cameras have come to enjoy widespread use in recent years. Such image capture devices employ image capture elements that are adapted to convert light received via a lens into an electrical signal. CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor) sensors, and the like are commonly used image capture elements of this kind. Such image capture elements are furnished with a plurality of photodetector elements (photodiodes) corresponding to the plurality of pixels that make up the photographed image, and are adapted to output image data that represents a respective pixel value of each pixel. When an image taken by an image capture device is displayed on a display device, if for example any of the photodetector elements should experience improper operation during shooting, resulting in output of pixel data of a higher value than the correct value for output, the pixel corresponding to the photodetector element in question may appear as a so-called bright defect, whereas if pixel data of a lower value than the correct value for output is output, the pixel corresponding to the photodetector element in question may appear as a so-called dark defect.
In order to correct through signal processing the image degradation that can result from such defective pixel image data, it was conventional practice at the semiconductor production facility to detect and save to nonvolatile memory beforehand defective pixel data for any defective pixels contained in an image capture element; and during normal shooting to determine, using a comparator circuit on the basis of addresses stored in the nonvolatile memory, whether current pixel data is associated with a defective pixel, and if determined to be associated with a defective pixel, to then perform correction of the defective pixel, for example, through substitution of the image capture output for the previous pixel in place of the image capture output for the defective pixel defective pixel as disclosed in JP-A 2006-100913.
Pixel counts required by more recent image capture elements have now reached a million or more pixels, up from several hundred thousand pixels in previous models, and despite advances in image capture element production technology, the number of defective pixels appearing in image capture elements has tended to increase accordingly.
For this reason, the scale of the comparator circuit has become larger in association with the increased the number of defective pixels. This has not only resulted in larger scale of the comparator circuit, but also led to the problem of delayed processing time and degraded image quality due to the larger number of determinations needing to be made.